The way the C6000 chip is controlled, it has to be configured to send or not send every 30mS during transmission.
So the only way the firmware could send on both Timeslots, would be if the Timeslot Interrupt Service Routine was not being run every 30mS. But if it was not being run, the Tx would not shut down either, as the same function handled Tx start and Tx stop as well as the Rx functionality
Simultaneous transmission on both time slots.
Re: Simultaneous transmission on both time slots.
Roger,
That was my thinking as well. It seems unlikely that it is really transmitting on both timeslots at the same time.
I guess that there is a faint possibility that it could be swapping between timeslots but even that seems unlikely. I certainly haven't seen any sign of that happening.
Colin
That was my thinking as well. It seems unlikely that it is really transmitting on both timeslots at the same time.
I guess that there is a faint possibility that it could be swapping between timeslots but even that seems unlikely. I certainly haven't seen any sign of that happening.
Colin
Re: Simultaneous transmission on both time slots.
The only thing I have seen the firmware doing, a long time ago, is miss identifying the TS, so that it randomly transmitted on to either TS1 or TS2.
But it did not transmit on both TS or swap TS during transmission.
But it did not transmit on both TS or swap TS during transmission.
Re: Simultaneous transmission on both time slots.
I currently have a Motorola DR3000 repeater in my workshop so I decided to do a few tests.
The Repeater has 2 LEDs on the front panel which indicate when the timeslots are active.
I tested many times with the GD77 on both timeslots.
The repeater never indicated incorrectly. The GD77 was always only transmitting on its selected timeslot.
I also tested with a Motorola SL4000 on one timeslot and the GD77 on the other. Again the operation was exactly as it should be.
I then looked at the output of the GD77 and the Motorola using a diode detector into a scope. This shows the RF envelopes and the relative timing of the two timeslots being sent to the repeater.
The SL4000 is the larger of the two signals, the OpenGD77 is the smaller. (the amplitude is not relevant, the difference was deliberate to identify the two signals).
You can clearly see the two timeslots and that the signal from the GD77 occurs in the gaps between the SL4000 transmissions. No timeslot overlap is present.
Based on these tests I can not see any evidence of the original reported issue.
Colin G4EML
The Repeater has 2 LEDs on the front panel which indicate when the timeslots are active.
I tested many times with the GD77 on both timeslots.
The repeater never indicated incorrectly. The GD77 was always only transmitting on its selected timeslot.
I also tested with a Motorola SL4000 on one timeslot and the GD77 on the other. Again the operation was exactly as it should be.
I then looked at the output of the GD77 and the Motorola using a diode detector into a scope. This shows the RF envelopes and the relative timing of the two timeslots being sent to the repeater.
- BothSlots.png (11.35 KiB) Viewed 4672 times
You can clearly see the two timeslots and that the signal from the GD77 occurs in the gaps between the SL4000 transmissions. No timeslot overlap is present.
Based on these tests I can not see any evidence of the original reported issue.
Colin G4EML
Re: Simultaneous transmission on both time slots.
Hi Roger and Colin, sorry to still pester and thank you both for your kind support!
In order not to disturb other users, I thin the tests over time and keep them short, maybe prolonging and intensifying them I could also be able to listen to myself, but right now I can not be sure.
the radio frequency emitted saturates the scanner receiver which is located not so far to the transceiver and the scanner too has to be connected to an antenna in order to receive back the repeater...
In fact in such a scenario I found little reliability and repeatability, which led me to use another different system to evaluate the matter.
By waiting to have both time slots free I tried to commit one of them and when this thing of the simultaneous transmission on both time slots occurred (which occurs very often but which is still random, there are cases in which it does not happen) I tried to hear myself on the other time slot, but I did not succeed.
As I have written before this thing of the simultaneous use of the two time slots seems to occur only if the time slot not used by the transmission is free, if it is busy the thing does not happen.
For example, while purposely transmitting on time slot 2 when time slot 1 is free, then simultaneous transmission could occur on both time slots, while if time slot 1 were busy, this could not happen.
This is what I was able to find with my tests.
However, the fact that I was unable to listen to myself may have been due to another oddity that I pointed out, a fact not really related to the possible simultaneous engagement of the two time slots, namely that if I transmit through the bridge on the TG9 (LOCAL) using the factory firmware from Radioddity, the GD-77 with the firmware Open set on the same time slot it intercepts the transmission, while instead doing the same thing with the latter one, then the GD-77 with the factory firmware from Radioddity does not hear anything, not even enabling the promiscuos mode.
Same thing if I use a tactical channel (TAC), although the codeplugs are surely correct (because by monitoring the transmission on the BrandMeister dashboard no error is displayed and I can also listen to myself online: https://hose.brandmeister.network/group/222003/), but anyway the two transceivers do not listen bilaterally each other, only the one with original firmware towards that with Open firmware.
Note:
IZ2EIB DMR id 2222828 is the first GD-77 on which is running Open firmware [3cb5e7] that I am using for testing.
IZ2KNZ DMR id 2222857 is the second GD-77 on which is running factory firmware from Radioddity that I am using for testing
So instead I did a different test.
On time slot 2 I activated an TG on demand, then from a different TG (either static or on demand, it does not matter) on time slot 1 I have started a disconnection (TG4000) and happening this fact of simultaneous transmission on both time slots then also the TG on time slot 2 was disconnected: therefore surely when the fact occurs, interference is created on the other time slot!
I cannot exclude that this thing of the simultaneous transmission on both time slots can be traced back to something wrong on the local repeater, though what I see is that by monitoring the BM dashboard no other user with any device has the same problem and that with the factory firmware from Radioddity the two GD-77s that I have here do not give problems, so something different must be there.
Probably the hardware of that two GD-77s I have, which however do not differ much from each other as a serial number, is different from that of the GD-77s of other users, I would not know what else to think, since I seem to be the only one to be plagued by the matter.
Then I noticed also one more thing, namely that with the original firmware from Radioddity by disconnecting with TG4000 the repeater reply by sending a pre-recorded synthesized voice message, while with the Open firmware no vocal warning is sent although the disconnection is successful.
Yes, I know, I mentioned it for reference only.
I am aware that this is a limitation of the GD-77's hardware and that it is already miraculous to have reached the point where we are thanks to the very hard work of you firmware developers.
Mine did not want to be a criticism.
Thanks!
Sadly from my side I can only rely on what I infer with my tests by looking at the BrandMeister dashboard, I have no other way.
Surely there is something because with the factory firmware from Radioddity I have never noticed the anomaly and even now, repeating the tests, I do not find anything weird.
I tried to load a very simple codeplug, a couple of channels, both for the Open firmware and for the Radioddity one and the results are what I have described.
I see that the Open firmware is light years ahead of the factory one from Radioddity and I would like to be able to use it, but sadly with my GD-77 I have the problems that I have described here in the forum.
I must also make clear that with the second GD-77 I have now here I had no problem switching from the factory firmware from Radioddity to the Open one and vice versa, in contrast to the transceiver that I already owned that I had to unlock with the rescue firmware v3.1.5 from Radioddity, but in that case the problem was caused by something else which in the meantime has been fixed with the new releases of the firmware Open.
I must also say that to program my GD-77s I use the portable versions of the CPS Community Edition (for the official firmware from Radioddity) and CPS Open firmware (for the Open firmware), not the installed versions.
I do not know if that can make a difference (I guess it does not matter at all).
For me the next steps will be to use a different computer to program the GD-77s (firmware and codeplug) and see what happens with a different repeater.
Roger, Colin and all, thank you very much for your patient and kind support!
73 best regards de Fabio IZ2EIB
Sadly I can not say it for sure, but instead I am 100% sure that when I simultaneous transmit on both time slots I unintentionally interfere with the time slot I am not using, please read below.
In order not to disturb other users, I thin the tests over time and keep them short, maybe prolonging and intensifying them I could also be able to listen to myself, but right now I can not be sure.
I listen to the repeater, but honestly I agree with you that scanner is not the best way to replace a real DMR test set, because in order to hit and listen the repeater I need to transmit with some power and I can not use a dummy load in place of the GD-77's antenna, so that
the radio frequency emitted saturates the scanner receiver which is located not so far to the transceiver and the scanner too has to be connected to an antenna in order to receive back the repeater...
In fact in such a scenario I found little reliability and repeatability, which led me to use another different system to evaluate the matter.
This is exactly what I did.
By waiting to have both time slots free I tried to commit one of them and when this thing of the simultaneous transmission on both time slots occurred (which occurs very often but which is still random, there are cases in which it does not happen) I tried to hear myself on the other time slot, but I did not succeed.
As I have written before this thing of the simultaneous use of the two time slots seems to occur only if the time slot not used by the transmission is free, if it is busy the thing does not happen.
For example, while purposely transmitting on time slot 2 when time slot 1 is free, then simultaneous transmission could occur on both time slots, while if time slot 1 were busy, this could not happen.
This is what I was able to find with my tests.
However, the fact that I was unable to listen to myself may have been due to another oddity that I pointed out, a fact not really related to the possible simultaneous engagement of the two time slots, namely that if I transmit through the bridge on the TG9 (LOCAL) using the factory firmware from Radioddity, the GD-77 with the firmware Open set on the same time slot it intercepts the transmission, while instead doing the same thing with the latter one, then the GD-77 with the factory firmware from Radioddity does not hear anything, not even enabling the promiscuos mode.
Same thing if I use a tactical channel (TAC), although the codeplugs are surely correct (because by monitoring the transmission on the BrandMeister dashboard no error is displayed and I can also listen to myself online: https://hose.brandmeister.network/group/222003/), but anyway the two transceivers do not listen bilaterally each other, only the one with original firmware towards that with Open firmware.
- 28122019.jpg (114.06 KiB) Viewed 4646 times
- 28122019 .jpg (148.32 KiB) Viewed 4646 times
IZ2EIB DMR id 2222828 is the first GD-77 on which is running Open firmware [3cb5e7] that I am using for testing.
- 3cb5e7f.png (2.58 KiB) Viewed 4646 times
So instead I did a different test.
On time slot 2 I activated an TG on demand, then from a different TG (either static or on demand, it does not matter) on time slot 1 I have started a disconnection (TG4000) and happening this fact of simultaneous transmission on both time slots then also the TG on time slot 2 was disconnected: therefore surely when the fact occurs, interference is created on the other time slot!
I cannot exclude that this thing of the simultaneous transmission on both time slots can be traced back to something wrong on the local repeater, though what I see is that by monitoring the BM dashboard no other user with any device has the same problem and that with the factory firmware from Radioddity the two GD-77s that I have here do not give problems, so something different must be there.
Probably the hardware of that two GD-77s I have, which however do not differ much from each other as a serial number, is different from that of the GD-77s of other users, I would not know what else to think, since I seem to be the only one to be plagued by the matter.
Then I noticed also one more thing, namely that with the original firmware from Radioddity by disconnecting with TG4000 the repeater reply by sending a pre-recorded synthesized voice message, while with the Open firmware no vocal warning is sent although the disconnection is successful.
Thanks Colin.
Yes, I know, I mentioned it for reference only.
I am aware that this is a limitation of the GD-77's hardware and that it is already miraculous to have reached the point where we are thanks to the very hard work of you firmware developers.
Mine did not want to be a criticism.
A very impressive work, Colin.
Thanks!
Sadly from my side I can only rely on what I infer with my tests by looking at the BrandMeister dashboard, I have no other way.
Surely there is something because with the factory firmware from Radioddity I have never noticed the anomaly and even now, repeating the tests, I do not find anything weird.
I tried to load a very simple codeplug, a couple of channels, both for the Open firmware and for the Radioddity one and the results are what I have described.
I see that the Open firmware is light years ahead of the factory one from Radioddity and I would like to be able to use it, but sadly with my GD-77 I have the problems that I have described here in the forum.
I must also make clear that with the second GD-77 I have now here I had no problem switching from the factory firmware from Radioddity to the Open one and vice versa, in contrast to the transceiver that I already owned that I had to unlock with the rescue firmware v3.1.5 from Radioddity, but in that case the problem was caused by something else which in the meantime has been fixed with the new releases of the firmware Open.
I must also say that to program my GD-77s I use the portable versions of the CPS Community Edition (for the official firmware from Radioddity) and CPS Open firmware (for the Open firmware), not the installed versions.
I do not know if that can make a difference (I guess it does not matter at all).
For me the next steps will be to use a different computer to program the GD-77s (firmware and codeplug) and see what happens with a different repeater.
Roger, Colin and all, thank you very much for your patient and kind support!
73 best regards de Fabio IZ2EIB
Re: Simultaneous transmission on both time slots.
Hello Fabio,
From your descriptions I would agree that it sounds like you are on both timeslots. But from studying the firmware and the radio I cannot see any explanation for that or any way that it could happen. So it looks like the problem is occurring at the repeater but it is strange that it only affects your signals and only with OpenGd77.
Looking at the Brandmeister pages it looks like the repeater is a Motorola DR3000. That is the same as I have in my workshop for testing.
It also says that the repeater is running firmware V2.10.00.11. I am wondering if that has something to do with it. That is quite old firmware and is not listed as 'tested' on the brandmeister site.
If I can find a copy of that old firmware I will see if I can load it into my test repeater. I do not know if it will let me go down in revision though so I may not be able to do that.
I am really running out of things to suggest. If you are travelling maybe you can repeat the experiment on a different repeater if there is one close enough.
73
Colin.
From your descriptions I would agree that it sounds like you are on both timeslots. But from studying the firmware and the radio I cannot see any explanation for that or any way that it could happen. So it looks like the problem is occurring at the repeater but it is strange that it only affects your signals and only with OpenGd77.
Looking at the Brandmeister pages it looks like the repeater is a Motorola DR3000. That is the same as I have in my workshop for testing.
It also says that the repeater is running firmware V2.10.00.11. I am wondering if that has something to do with it. That is quite old firmware and is not listed as 'tested' on the brandmeister site.
If I can find a copy of that old firmware I will see if I can load it into my test repeater. I do not know if it will let me go down in revision though so I may not be able to do that.
I am really running out of things to suggest. If you are travelling maybe you can repeat the experiment on a different repeater if there is one close enough.
73
Colin.
Re: Simultaneous transmission on both time slots.
Hello everybody,
I noticed that this thing sometimes happens to me on the ir4ubo repeater too. The repeater is a motorola dr3000, while on the ir4mo repeater (Hytera RD985) it never happened.
Firmware December 27, 2019 3cb5e7f
73 IU4LEG Fabio
I noticed that this thing sometimes happens to me on the ir4ubo repeater too. The repeater is a motorola dr3000, while on the ir4mo repeater (Hytera RD985) it never happened.
Firmware December 27, 2019 3cb5e7f
73 IU4LEG Fabio
Re: Simultaneous transmission on both time slots.
Hi guys.
@Colin
Many thanks for the the trouble you took in order to do your investigations and considerations you have exposed, you are really very kind!
I will try to contact the Sysops by submitting the matter.
I have no experience with that kind of thing, but if I understood correctly it would be a matter of trying to update the repeater's firmware, which, however, I do not know if it is easy or hard to do.
I guess that the update is doable, but I am not sure that the upgrade firmware is free and I guess that the repeater too will have to be reprogrammed.
I will try to write to Sysop about all this things.
Of course I will try to test the thing with other repeaters especially BrandMeister, but also of other kinds.
It is still weird, as with the factory firmware from Radioddity I have never found it and in any case I have never seen the problem even by other users who use different models of DMR terminal and also of other brands.
Also the lack in bilateral communication between GD-77s with stock firmware from Radioddity and the Open one while transiting through the repeater, in example by engaging the TG9 (LOCAL) or TACs, could be consequent of the obsolete firmware of the Motorola DR3000 repeater, even if it is a mystery why in the same scenario with the factory firmware from Radioddity the two GD-77s talk each other without problems and the Motorola DR3000's firmware is always the same, even if obsolete.
A thought of mine is that since the problem is there and it is real, it means that potentially in a totally unconscious way any DMR user could create problems to the network, even considering the large amount of repeaters whose firmware may not be updated and therefore obsolete.
Thanks Colin!
@Fabio
Thanks my namesake!
What you wrote relieves me, so I am not the only one who noticed the thing.
Do you remember ever seeing the problem even while using the stock firmware from Radioddity?
The answer could be useful to know, as I believe that, beyond the fact that it would be better the repeater's firmware was always updated in the limit of the possible, it could be interesting to understand what in the factory firmware from Radioddity prevents the onset of the problem regardless of the firmware revision running on the repeater.
My personal opinion.
Thanks Fabio!
73 best regards de Fabio IZ2EIB
@Colin
Many thanks for the the trouble you took in order to do your investigations and considerations you have exposed, you are really very kind!
I will try to contact the Sysops by submitting the matter.
I have no experience with that kind of thing, but if I understood correctly it would be a matter of trying to update the repeater's firmware, which, however, I do not know if it is easy or hard to do.
I guess that the update is doable, but I am not sure that the upgrade firmware is free and I guess that the repeater too will have to be reprogrammed.
I will try to write to Sysop about all this things.
Of course I will try to test the thing with other repeaters especially BrandMeister, but also of other kinds.
It is still weird, as with the factory firmware from Radioddity I have never found it and in any case I have never seen the problem even by other users who use different models of DMR terminal and also of other brands.
Also the lack in bilateral communication between GD-77s with stock firmware from Radioddity and the Open one while transiting through the repeater, in example by engaging the TG9 (LOCAL) or TACs, could be consequent of the obsolete firmware of the Motorola DR3000 repeater, even if it is a mystery why in the same scenario with the factory firmware from Radioddity the two GD-77s talk each other without problems and the Motorola DR3000's firmware is always the same, even if obsolete.
A thought of mine is that since the problem is there and it is real, it means that potentially in a totally unconscious way any DMR user could create problems to the network, even considering the large amount of repeaters whose firmware may not be updated and therefore obsolete.
Thanks Colin!
@Fabio
Thanks my namesake!
What you wrote relieves me, so I am not the only one who noticed the thing.
Do you remember ever seeing the problem even while using the stock firmware from Radioddity?
The answer could be useful to know, as I believe that, beyond the fact that it would be better the repeater's firmware was always updated in the limit of the possible, it could be interesting to understand what in the factory firmware from Radioddity prevents the onset of the problem regardless of the firmware revision running on the repeater.
My personal opinion.
Thanks Fabio!
73 best regards de Fabio IZ2EIB
Re: Simultaneous transmission on both time slots.
Fabio,
At the moment it is only a guess that the firmware is the cause. From your description it does sound like the openGD77 firmware is doing something different to the stock firmware. But I can’t think what that could be.
Colin.
At the moment it is only a guess that the firmware is the cause. From your description it does sound like the openGD77 firmware is doing something different to the stock firmware. But I can’t think what that could be.
Colin.